Garlemald is more in-depth than many credit. The issue isn't that they're 'generic bad guys' - because they aren't. Neither Gaius or Regula were shown to be completely irredeemable. The issue with Garlemald from a story perspective is that the developers are taking far too long to get to the rather predictable point where we put aside our differences and team up with them to deal with the greater threat that is the Ascians. The story is slowly heading in that direction. We just need more focus to be put on the simple fact that Pureblood Garleans are acting the way that they do because they have been persecuted throughout history right up until they decided enough was enough and put themselves first. Furthermore, Garlemald never had the luxury of a 'Warrior of Light' to conveniently solve all its issues. Eorzea does, thus Eorzea never has to ever be at risk of truly dirtying its hands.
With that said, Zenos did feel like he was creating purely to justify reclaiming Doma and Ala Mhigo with no real backlash. It never felt like a war. Personally, I find the likes of Hingashi and Garlemald far more engaging than Eorzea because the bulk of the Eorzea story has revolved around plot points that led to no real payoff. Ul'dah was given the lion's share of attention...only for everything to wrap up neatly with no lasting consequences. Nanamo didn't die. Raubahn lost an arm...but it doesn't affect his fighting ability in the slightest. Teledji was the only real loss and that was of great benefit to the protagonists.
Ideally, Garlemald's story will go in a similar direction to how things played out with the Archadian Empire back in FFXII. Or, perhaps, the Shinra Corporation from FF7. In both games, they served the purpose of major antagonists but as we learned more about each we realised things weren't so black or white. By the end of each game's story both aren't eradicated - they undergo some reforms, but don't lose their 'bite' or influence. I believe things are heading in that direction, though. My predictions regarding Garlemald have been spot on so far. When many people were convinced that Regula was going to be 'Kefka' I called him being an honourable figure instead...and that is what happened. When Yotsuyu and Fordola were considered as having no redeeming qualities I stated that we'd see things from their perspective...and we did. I also said we'd spent time working alongside more and more Garleans...which is what happened with the crew of the Prima Vista as well as Maxima.